Antimicrobial drywall

Abstract

Antimicrobial guanidine compounds are used, either alone or with at least one other antimicrobial compound, to make mildew-resistant wallboard. Particularly useful co-additives are o-phenyl phenol and sodium methyldithiocarbamate. The antimicrobial compound(s) may be added to the covering, the core body, an adhesive at the interface of the core body and the covering, or all three of these sites. A preferred guanidine compound is dodecyl guanidine hydrochloride.

1 . A wallboard which inhibits the growth of microbes, said wallboard comprising a gypsum core and at least one covering, said wallboard having incorporated therein an antimicrobial guanidine compound.  
   
   
       2 . The wallboard of  claim 1  wherein said antimicrobial guanidine compound comprises dodecyl guanidine hydrochloride.  
   
   
       3 . The wallboard of  claim 1  wherein said antimicrobial guanidine compound is present in said wallboard at a concentration of at least 10 parts by weight antimicrobial guanidine compound to one million parts by weight wallboard.  
   
   
       4 . The wallboard of  claim 1  wherein said covering is a paper covering and said antimicrobial guanidine compound is present in said paper covering.  
   
   
       5 . The wallboard of  claim 1  wherein said antimicrobial guanidine compound is present in said core body.  
   
   
       6 . The wallboard of  claim 1  wherein said antimicrobial guanidine compound is present on the surface of said covering.  
   
   
       7 . The wallboard of  claim 1  having an interface between said core body and said paper covering, and including a material capable of providing nourishment to microbes at said interface, and wherein said antimicrobial guanidine compound is also present at said interface.  
   
   
       8 . The wallboard of  claim 1  having also incorporated therein sodium methyldithiocarbamate.  
   
   
       9 . The wallboard of  claim 1  having also incorporated therein an antimicrobial phenolic compound.  
   
   
       10 . The wallboard of  claim 9  wherein said antimicrobial phenolic compound is ortho phenyl phenol or its sodium salt and is present in said wallboard in a total concentration of at least 10 parts by weight per million parts by weight of said wallboard.  
   
   
       11 . The wallboard of  claim 8  wherein said sodium methyldithiocarbamate and said antimicrobial guanidine compound are present in said wallboard in an antimicrobially synergistic ratio.  
   
   
       12 . The wallboard of  claim 9  wherein said antimicrobial guanidine compound and said antimicrobial phenolic compound are present in or on said covering.  
   
   
       13 . The wallboard of  claim 11  wherein said sodium methyldithiocarbamate and said antimicrobial guanidine compound are present in or on said covering.  
   
   
       14 . The wallboard of  claim 1  wherein said antimicrobial guanidine compound is dodecyl guanidine hydrochloride and wherein ortho phenyl phenol is also present in said wall board in an antimicrobially synergistic ratio to said dodecyl guanidine hydrochloride..  
   
   
       15 . Wallboard of  claim 1  wherein said core body comprises gypsum.  
   
   
       16 . A method of making mildew-resistant wallboard comprising adding an antimicrobial guanidine compound to at least one component of said wallboard during the manufacture of said wallboard.  
   
   
       17 . The method of  claim 16  wherein said antimicrobial compound is dodecyl guanidine hydrochloride.  
   
   
       18 . The method of  claim 16  including adding a second antimicrobial additive to at least one component of said wallboard during the manufacture of said wallboard.  
   
   
       19 . A method of making a mildew-resistant paper covering for wallboard comprising adding an antimicrobial guanidine compound to said paper during or after manufacture of said paper covering.  
   
   
       20 . The method of  claim 19  wherein said antimicrobial guanidine compound is dodecyl guanidine hydrochloride.